The invention relates generally to electrochemical devices having improved performance. In particular, the invention relates to electrode structures employed in the electrochemical devices and methods of making the same.
A solid oxide fuel cell (SOFC) is an electrochemical device that converts chemical energy of a fuel (such as hydrogen) and an oxidizer (such as air or oxygen) into electricity. In principle, the SOFC works like a battery, however, unlike a battery, the SOFC does not run down or require recharging. This is one of the reasons that solid oxide fuel cells (SOFCs) are considered as a viable option for clean and effective power generation.
As will be appreciated, a SOFC produces electricity by catalyzing fuel and oxidant into ionized atomic hydrogen and oxygen at the anode and cathode, respectively. The electrons removed from hydrogen in the ionization process at the anode are conducted to the cathode where they ionize the oxygen. This reaction takes place at triple phase boundaries formed between the cathode material, electrolyte and gas. Subsequently, the oxygen ions are conducted through the electrolyte where they combine with ionized hydrogen to form water as a waste product and complete the process. This series of electrochemical reactions provides the mechanism for generating electric power within the SOFC.
As will be appreciated, the efficiency of a SOFC is often limited by the efficiency of the electrodes in conducting this series of reactions. Disadvantageously, current materials for SOFC cathodes are limited by the rate of adsorption and dissociation of the oxygen molecules before they are incorporated in the solid oxide electrolyte at triple phase boundaries, thereby increasing the over-potential that limits the power output and the temperature at which the SOFC can operate.
Accordingly, it is desirable to have a material at the triple phase boundaries that accelerates the rate of reactions at the electrodes, such as oxygen adsorption and reduction at the cathode.